1. FIELD OF THE INVENTION
The present invention relates to bicycle drive chain guides, and more particularly, it relates to a drive chain guide for bicycles having gear shifting capability wherein the guide keeps the chain on the sprocket during a gear shift to the inner chain ring and can be adjusted with respect to its location adjacent to the chain for preventing it from derailing.
2. DESCRIPTION OF THE PRIOR ART
The only known prior art bicycle drive chain guide is a metal bar which can be secured to the frame of the bicycle and fixed in position proximate the chain whereby as a chain begins to derail from the inner sprocket, the bar restricts the chain displacement whereby it is guided to stay in alignment on the inner chain ring or drive sprocket. A metal bar is a very crude guide and does not offer a range of positioning adjustment except by squeezing a rubber mount during tightening of the mounting bolts which thereby adjusts the positioning of the guide with respect to its attachment to the bicycle frame to a small degree very inaccurately. Different sized units must be used for different diameters of bicycle frame tubing. The prior art does not provide a device with a wide range of adjustment which is easily secured in position to a range of bicycle frame tubing sizes and quickly and easily adjusted with respect to its spacing to the bicycle drive chain.